Effects of nitrogen enrichment on wood decomposition
Data files
Sep 04, 2026 version files 37.48 KB
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DairyOne_lignin_results.xlsx
11.63 KB
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decomp_cleaned.csv
12.51 KB
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FWD_decomp_cleaned.csv
2.46 KB
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overall_log_C_N.csv
1.96 KB
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overall_soil_C_N.csv
2.11 KB
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README.md
6.82 KB
Abstract
Nitrogen deposition supplements forest nutrient cycles, but levels vary with proximity to human activity. To assess its influence in remote Southern Appalachian forests, this study examined woody debris decomposition of Liriodendron tulipifera and Pinus strobus under control and nitrogen enrichment (5 kg N ha⁻¹ yr⁻¹) treatments over one year. Logs (5 cm diameter) and sticks (< 5 cm diameter) were evaluated for mass and density changes, and logs were further analyzed for wood chemistry (lignin, cellulose, hemicellulose, C, and N). Wood species emerged as the dominant driver of early decomposition, with L. tulipifera and P. strobus differing in lignin and cellulose content. Nitrogen enrichment had little effect, except in one-year L. tulipifera logs, which showed higher lignin concentrations—possibly reflecting delayed decay. These findings suggest that while wood chemistry dictates early-stage decomposition, low-level N additions may exert subtle, species-specific effects. Longer-term studies are needed to identify thresholds at which N enrichment alters decomposition, an important consideration as global change reshapes forest nutrient regimes and carbon storage potential.
Dataset DOI: 10.5061/dryad.zpc866tnk
Description of the data and file structure
Six 30 m × 30 m plots were established across three elevations (low, mid, high) in both coniferous and deciduous forests. A two-way fixed block design stratified plots by forest type and elevation. Within each plot, two 2 m × 4 m subplots were designated for nitrogen (N) enrichment and control. Time-released urea was applied quarterly in treatment plots to simulate N deposition of 5 kg N ha⁻¹ yr⁻¹.
The decomposition experiment compared Liriodendron tulipifera (tulip poplar; TP) and Pinus strobus (white pine; WP). In each subplot, four logs (15 cm long, ~15 cm circumference) were placed on the soil surface, and mesh litterbags containing fine woody debris (FWD) were installed. TP was placed in deciduous plots and WP in coniferous plots. Logs were harvested after 6 and 12 months; FWD after 6 weeks, 3 months, and 12 months. Soil cores (10 cm deep) were collected beneath each log at harvest.
In the lab, logs were weighed, oven-dried, drilled for wood shavings, and cut into disks for chemical analyses. Shavings were analyzed for C and N content, while disks were analyzed for lignin, cellulose, and hemicellulose. FWD was assessed for mass loss only.
Files and variables
File: DairyOne_lignin_results.xlsx
Description: Results for the log chemical properties: lignin, cellulose, and hemicellulose. The blanks in the elevation and treatment columns refer to the fact that these logs were left out as controls (i.e., were not placed in the field for decomposition). Note: ADF – Lignin = cellulose & NDF – ADF = hemicellulose
Variables
- label: label obtained from lab
- tree: TP (tulip poplar, Liriodendron tulipifera) and WP (white pine, Pinus strobus)
- harvest: harvest time (12 vs. 0 months)
- forest: D (deciduous forest) and C (coniferous forest)
- elevation: H (high), L (low), M (middle)
- treatment: C (control), N (nitrogen enrichment)
- moisture_percent: the amount of moisture for each log
- dry_matter_percent: the amount of dry matter for each log
- ADF: percent of plant material from ADF test (acid detergent fiber)
- aNDF: percent of plant material from aNDF test (acid detergent neutral fiber)
- lignin: % lignin content
File: decomp_cleaned.csv
Description: Data showing the amount of decomposition of each log by evaluating mass loss and density changes over the study period.
Variables
- log_number: ID # for each log
- tree_sp: TP (tulip poplar, Liriodendron tulipifera) and WP (white pine, Pinus strobus)
- forest: D (deciduous forest) and C (coniferous forest)
- elevation: H (high), L (low), M (middle)
- trt: C (control), N (nitrogen enrichment)
- harvest_date: the date of harvest
- initial_length (cm): the length of each log at the start of the study
- initial_circumference (cm): the circumference of each log at the start of the study
- initial_mass: the mass of the log at the start of the study (measured in g)
- length (cm): the length of the log after harvest
- circumference (cm): the circumference of the log after harvest
- diameter (cm): the diameter of the log after harvest
- wet_mass (g): the mass of the logs before being dried in an oven
- dry_mass: the mass of the logs after being dried in an oven
- wood_moisture (%): the percent moisture of the wood
- mass_loss (g): the difference in mass from the initial measurement to that at harvest
- log_total_N (%): the percent N measured for each log
- log_total_C (%): the percent C measured for each log
- soil_tot_N (%): the percent N measured for a soil sample obtained beneath a correlating log
- soil_tot_C (%): the percent C measured for a soil sample obtained beneath a correlating log
- initial_radius: the radius of each log at the start of the study
- initial_volume: the volume of each log at the start of the study
- new_radius: the radius of each log after harvest
- new_volume: the volume of each log after harvest
- corrected_initial_mass: correcting for the weight of the ID tags in the post-harvest mass
- mass_remaining: post-harvest mass calculation (measured as g)
- density: the calculated density of each log (measured as g/cm^3)
- harvest_months: correlating to harvest date (0, 6, 12 months)
NA: not applicable; measurements not required for statistical analysis with this dataset
File: overall_log_C_N.csv
Description: The results from DairyOne lab as to the carbon and nitrogen content found within each log.
Variables
- log_number: ID # for each log
- tree_sp: TP (tulip poplar, Liriodendron tulipifera) and WP (white pine, Pinus strobus)
- forest: D (deciduous forest) and C (coniferous forest)
- elevation: H (high), L (low), M (middle)
- trt: C (control), N (nitrogen enrichment)
- harvest_date: date of harvest
- log_total_N (%): the percent N measured for each log
- log_total_C (%): the percent C measured for each log
File: overall_soil_C_N.csv
Description: The results from DairyOne lab as to the carbon and nitrogen content found within each soil sample (taken from beneath each log at the specified time of harvest).
Variables
- log_number: ID # for each log
- tree_sp: TP (tulip poplar, Liriodendron tulipifera) and WP (white pine, Pinus strobus)
- forest: D (deciduous forest) and C (coniferous forest)
- elevation: H (high), L (low), M (middle)
- trt: C (control), N (nitrogen enrichment)
- harvest_date: the date of harvest
- soil_tot_N: the percent N measured for each soil sample
- soil_tot_C: the percent C measured for each soil sample
File: FWD_decomp_cleaned.csv
Description: Data showing the amount of decomposition that occurred to fine woody debris (FWD, i.e., sticks).
Variables
- Tag number: ID # of the mesh bags the FWD was encompassed in
- Forest type: Deciduous vs. Coniferous
- Elevation: Low, Mid, High
- Treatment: Control vs. Fertilized
- Harvest: 1, 2, 3 (first, second, and third harvest times)
- Initial weight (g): the initial mass of the FWD at the beginning of the study
- Corrected initial: the corrected FWD mass
- Dry weight (g): the weight of the FWD after harvest and being dried in an oven
- Mass remaining (%): the calculated mass remaining in relation to the initial mass to understand how much decomposition has occurred in the FWD
Code/software
All analyses were performed in R version 2023.12+369 (R Core Team 2023). We used three-way ANOVAs to test if there was an impact of log species, N treatment, or harvest time, and their interaction on the woody mass loss of logs and FWD, log tissue properties (i.e., lignin, cellulose, and hemicellulose content), and log C and N content (R package stats).